UNIVERSITY    OF    CALIFORNIA 

COLLEGE    OF   AGRICULTURE 

AGRICULTURAL    EXPERIMENT    STATION 

BERKELEY,    CALIFORNIA 

CIRCULAR  294 

August,  1925 

PROPAGATION  OF  DECIDUOUS   FRUITS 

J.  L.  STAHL 


Strictly  speaking  there  is  no  single  way  in  which  a  particular  fruit 
must  be  propagated.  For  example,  apple  trees,  which  are  usually 
budded  in  California  might  be  grafted  or,  conceivably,  grown  from 
hardwood  cuttings,  softwood  cuttings,  or  even  from  layers.  How- 
ever, budding  is  usually  cheaper  than  grafting,  and  it  is  impractical 
to  use  either  cuttings  or  layers  on  account  of  the  trouble  and  expense. 
The  methods  that  nurserymen,  florists,  and  others  use  in  propagating 
plants  are  the  result  of  long  years  of  experience  and  are  based  on 
convenience  and  cost  of  operation.  Sometimes  it  is  more  convenient 
or  cheaper  to  use  one  method  and  sometimes  another.  Certain  methods 
have  become  standard  for  particular  fruits  and  these  methods  will  be 
described  in  this  circular. 

It  frequently  happens  that  a  fruit  grower  or  farmer  needs  to  make 
use  of  a  method  to  suit  his  particular  conditions  that  would  not  be 
practical  for  a  nurseryman  to  use  on  a  commercial  scale — for  example, 
the  propagation  of  a  favorite  vine  or  shrub.  This  can  be  easily  accom- 
plished by  drawing  down  a  branch  and  covering  it  with  earth  until  it 
takes  root.  The  layered  part  is  then  cut  away,  thus  producing  a 
separate  plant.  The  nurseryman,  on  the  other  hand,  could  not  afford 
the  time  nor  the  expense  to  propagate  on  so  small  a  scale  for  com- 
mercial purposes.  To  multiply  the  same  plant  on  a  large  scale  it 
would  be  necessary  to  resort  to  hardwood  cuttings  and  to  be  provided 
with  all  the  necessary  equipment  in  the  way  of  hotbeds,  coldframes, 
callus  pits,  etc.,  for  carrying  on  the  work. 

One  of  the  methods  of  propagation  most  frequently  used  is  that  of 
grafting  or  top-working  established  trees  in  the  orchard.  Every  fruit 
grower  has  to  resort  to  this  method  to  some  extent,  but  obviously  the 
nurseryman  makes  use  of  this  plan  only  in  a  limited  way  if  at  all, 
because  his  business  is  to  propagate  young  trees  to  sell,  and  merchant- 
able trees  at  the  nursery  are  never  more  than  one  or  two  years  old. 


2  UNIVERSITY    OF    CALIFORNIA — EXPERIMENT    STATION 

The  question  most  frequently  asked  is,  "Why  not  grow  all  fruits 
and  shrubs  from  seeds?"  The  answer  is  that  where  improvements 
have  been  made  these  qualities  are  not  transmitted  through  the  seed 
but  are  perpetuated  through  the  buds.  Hence  the  necessity  of  using 
parts  of  the  plant  itself  by  budding,  grafting,  and  layering.  If  we 
merely  desire  a  peach  or  plum  tree  without  regard  to  the  variety, 
seeds  may  be  used.  Occasionally  a  variety  will  come  true  to  type 
from  the  seed  as  does  the  old  Heath  Cling  peach,  but  such  cases  are 
rare.  In  propagating  fruits,  therefore,  seeds  are  used  only  for  grow- 
ing stock  plants  on  which  to  bud  or  graft  varieties.  This  is  true  for 
most  tree  fruits.  Some  stocks  are  profitably  grown  from  cuttings, 
such  as  quinces,  roses,  grapes,  and  certain  types  of  plums. 

The  question  of  what  kind  of  stocks  to  use  even  for  the  common 
deciduous  fruits  is  a  long  story  in  itself — much  too  long  to  be  narrated 
here  with  any  degree  of  completeness.  The  following  summary  must 
suffice : 

Apple. — Stocks  for  apples  may  be  grown  from  the  seeds  of  any 
variety  of  apple.  As  there  is  no  commercial  source  of  supply  in  this 
country  aside  from  very  limited  quantities  from  old  seedling  orchards 
in  New  England  referred  to  as  "Vermont  crab,"  nurserymen  procure 
their  seeds  from  France  and  Austria.  These  are  native  seedlings 
known  to  the  trade  as  "French  crab."  Stock  for  dwarf  apples 
consists  of  stool  or  mound  layers  from  the  Paradise  apple,  a  natural 
dwarf  type. 

Almonds. — In  producing  stock  for  the  almond,  seeds  of  bitter 
almond  are  commonly  used,  although  sweet  almonds  are  doubtless 
just  as  good.  Other  stocks  on  which  almonds  are  propagated  are 
peach  (any  variety),  and  occasionally  Myrobalan  (cherry  plum), 
although  the  latter  is  not  very  satisfactory. 

Apricots. — The  chief  stock  for  the  apricot  is  seedlings  of  apricot 
varieties.  Apricots  are  also  grown  on  Myrobalan  and  Prunus  mume 
(Japanese  apricot),  and  occasionally  on  peach,  although  the  last 
named  does  not  often  make  a  good  union. 

Cherries. — Mazzard  cherry  is  the  common  stock  for  sweet  cherries, 
and  Mahaleb  for  sour  varieties.  All  seeds  are  imported  from  France. 
A  sour  cherry  seedling,  known  as  the  Stockton  Morello,  is  coming  into 
favor  for  adapting  sweet  cherries  to  heavy  or  even  wet  soils  where 
the  stock  has  a  decidedly  dwarfing  influence. 

Peaches. — The  peach  is  chiefly  propagated  on  peach  seedlings.  In 
California  the  seeds  come  mainly  from  the  Salwey  and  Muir  varieties, 
although  it  is  probable  that  any  variety  would  do.  The  Strawberry, 
an  old  discarded  variety,  seems  to  give  the  highest  percentage  of 


CIRC.  294]  PROPAGATION    OF   DECIDUOUS   FRUITS  3 

germination  and  the  greatest  uniformity  of  seedlings.  Almond  seed- 
lings may  be  used.  Apricot  seedlings  are  occasionally  employed  in 
sandy  soils  to  resist  nematode  injury,  but  the  union  is  not  often  suc- 
cessful and  can  be  remedied  only  by  double-working,  using  Sugar 
prune  as  the  intermediate  stock.  The  peach  does  well  on  Prunus 
davidiana  (wild  Chinese  peach),  which  is  distinctly  tolerant  of  alkali. 

Pears. — The  chief  stock  for  pears  is  grown  from  a  native  seedling 
of  Europe  known  as  the  French  pear.  The  Chinese  sand  pear,  known 
to  the  trade  as  "Japanese  pear,"  has  been  a  failure  in  California, 
because  it  does  not  thrive  in  heavy  or  wet  soils.  The  Manchurian 
species,  Pyrus  ussuriensis  and  Pyrus  calleryana,  are  sparingly  used 
as  blight-resistant  stocks,  as  the  seeds  which  come  from  Japan  are  apt 
to  be  mixed  with  other  species  which  are  not  resistant  to  blight.  Two 
blight -resistant  varieties,  the  Old  Home  and  Surprise,  may  be  bench- 
grafted  on  French  seedling  roots  and  later  top-worked  to  Bartlett  or 
any  other  desired  variety.  This  makes  it  impossible  for  blight  to  do 
more  than  kill  the  branches,  which  may  again  be  top-grafted.  The 
French  root  is  the  only  pear  stock  known  to  be  highly  resistant  to  oak 
fungus. 

Plums  and  Prunes. — Plums  and  prunes  are  grown  principally  on 
Myrobalan  seedlings.  The  seeds  are  imported  from  Italy  by  way  of 
France,  although  scattering  trees  from  which  seeds  might  be  procured 
may  be  found  in  any  old  prune  or  plum  orchard  in  California.  Peach 
seedlings  are  also  a  common  stock.  The  almond  is  used  especially  in 
the  Sierra  foothills. 

Walnuts. — Seedlings  of  the  wild  Northern  California  black  walnut 
are  used  almost  exclusively  as  stock  for  walnuts  because  they  answer 
every  purpose  including  resistance  to  oak  fungus.  Seedling  English 
walnuts  may  be  used,  though  they  are  less  hardy  and  are  readily 
attacked  by  oak  fungus.  Hybrids  between  the  California  and  Eastern 
black  walnuts,  or  between  either  of  these  and  the  English  walnut  are 
unusually  vigorous  growers,  if  selected  stock  is  used.  They  are,  how- 
ever, rarely  utilized  because  of  the  difficulty  in  obtaining  the  nuts 
or  seedlings  for  planting. 

The  principal  methods  of  propagating  deciduous  fruits  are  by 
budding,  grafting,  hardwood  cuttings,  layering,  root  suckers,  and 
seeds. 

BUDDING 

Budding  is  the  operation  of  inserting  a  single  detached  bud  under 
the  bark  of  the  stock  or  seedling.  Buds  are  taken  from  the  current 
season's  growth  of  the  tree  desired  and  placed  on  seedlings  in  the 
nursery.     Only  wood  buds  are  used,  since  flower  buds  would  only 


4  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

blossom  and  die.  Wood  buds  are  always  smaller  and  sharper-pointed 
than  flower  buds.  Where  they  occur  in  clusters  the  center  one  is 
practically  always  a  wood  bud.  Single  buds  are  preferred  for 
budding.  Where  clusters  are  used  the  outside  buds  are  rubbed  off. 
The  budding  knife  should  be  of  good  steel  and  with  a  thin  blade 
having  an  upward  curve  to  the  cutting  edge. 

Apples,  pears,  and  quinces  may  be  either  budded  or  grafted.  On 
the  Pacific  Coast,  they  are  usually  budded,  while  in  the  East  they 
are  often  bench-grafted,  the  work  being  done  in  a  grafting  cellar  in 
winter  (January  and  February).  Stone  fruits,  such  as  almonds, 
apricots,  cherries,  peaches,  and  plums,  are  commonly  budded. 

The  operation  of  budding  is  simple  and  easily  learned,  but  skill  is 
acquired  only  after  much  practice.  Budding  is  usually  done  in  the 
latter  part  of  July  or  August  when  the  bark  peels  readily,  but  may 
be  continued  through  September  or  until  the  bark  refuses  to  peel. 
When  the  nursery  trees  are  %6  to  %  inch  in  diameter  all  leaves  and 
branches  within  six  inches  of  the  ground  are  rubbed  off.  This  opera- 
tion should  not  be  performed  within  a  week  or  ten  days  of  budding 
as  the  wounds  must  have  time  to  heal.  Buds  from  the  variety  desired 
are  secured  by  cutting  " whips"  or  twigs  of  last  season's  wood.  For 
convenience  in  handling,  these  whips  are  trimmed  from  the  sticks 
with  a  sharp  knife,  cutting  the  stem  from  the  underside.  Beginners 
will  find  it  desirable  to  cut  the  leaf  stems  to  stubs  a  quarter  of  an 
inch  long  for  ease  in  handling. 

Bud  sticks  should  be  kept  moist  from  the  time  they  are  taken  from 
the  tree  until  budding  is  done.  They  may  be  wrapped  in  wet  burlap 
and  kept  standing  in  a  pail  with  a  few  inches  of  water.  In  nursery 
practice,  buds  are  usually  placed  on  the  north  side  of  the  seedlings 
for  protection  against  the  sun  and  as  near  the  ground  as  it  is  con- 
venient to  work.  In  parts  of  California  where  summer  north  winds 
are  hot,  some  propagators  prefer  to  bud  on  the  south  side  of  the 
nursery  tree,  believing  that  exposure  to  the  sun  is  less  harmful  to  the 
bud  than  the  hot  north  wind. 

Modified  Shield  Bud. — A  modified  shield  bud  is  most  commonly 
used.  The  bud  with  half  an  inch  of  bark  and  a  thin  layer  of  wood  is 
sliced  from  the  bud  stick  with  a  sharp  knife  and  immediately  placed 
beneath  the  bark  in  contact  with  the  cambium  or  growing  layer  (fig. 
1.)  The  matrix  for  receiving  the  bud  is  usually  made  ready  before  the 
bud  is  cut  from  the  stick.  Two  slits  are  made  on  the  trunk  of  the 
seedling  about  two  inches  from  the  ground.  One  of  the  slits  is  cut 
across  the  stem  and  the  other  up  and  down  at  right  angles  to  the  first, 
either  above  or  below  it,  thus  forming  the  letter  T  upright  or  inverted. 


Circ.  294] 


PROPAGATION    OF    DECIDUOUS   FRUITS 


Expert  budders  make  the  final  vertical  slit  and  throw  open  the  bark 
ready  to  receive  the  bud  all  at  one  stroke  or  with  a  single  movement 
and  without  removing  the  knife  blade. 


i 


)■ 


Fig.  1. — Bud  sticks  and  buds.     The  buds  are  partially  cut  away  but  not 
entirely  removed  from  the  sticks  until  actually  needed. 


To  set  the  bud,  place  it  point  up  under  the  flaps  of  the  bark  in 
the  T.  Tie  firmly  with  a  twelve-inch  piece  of  cotton  wrapping  twine 
or  wet  raffia.  Wrap  it  at  least  twice  around  both  below  and  above  the 
the  bud.  The  loose  ends  may  be  tied  in  a  single  knot,  or  if  wrapping 
is  done  from  one  end  only,  as  is  customary  with  skillful  operators,  the 
other  may  be  made  secure  at  the  finish  by  a  half  hitch.     In  ten  days 


D  UNIVERSITY    OF    CALIFORNIA EXPERIxVIENT    STATION 

or  two  weeks  the  string  should  be  cut  so  that  the  bark  will  not  be 
constricted.     Nothing  more  need  be  done  until  spring   (fig.  2). 

Successful  budding  cannot  be  done  unless  the  bark  of  the  stock 
peels  readily.  It  is  not  so  necessary  for  the  bark  to  peel  on  the  bud 
stick.    For  this  reason  the  modified  shield  bud  is  used  rather  than  the 


Fig.   2. — Steps  in  setting  a  shield  or  modified  shield  bud.     Left,   T   cut 
made  in  bark;  center,  buds  shown  in  place;  right,  bud  tied. 


true  shield  bud.  To  remove  from  the  stick,  a  deep  slice  is  made 
beneath  the  bud  and  extending  just  beyond  it  when  the  blade  is  with- 
drawn and  a  light  horizontal  cut  macle  just  through  the  bark.  The 
bud  with  its  shield-shaped  piece  of  bark v  can  then  be  lifted  off  with 
the  thumb  and  finger,  leaving  the  wood  behind.  This  is  the  true  shield 
bud  with  a  square  shouldered  top  and  the  pointed  bottom. 

When  growth  starts  in  the  spring,  the  seedlings  should  be  cut  back 
to  one-half  inch  above  the  bud,  and  all  sprouts  appearing  below  the 
bud  rubbed  off.  One  season's  growth  from  the  bud  should  develop  a 
tree  large  enough  for  orchard  planting. 

June  Budding. — Peach  seedlings  are  often  large  enough  to  be 
budded  in  May  or  early  June  and  set  in  the  orchard  the  following 
spring,  thus  gaining  a  year.  When  this  is  done,  it  is  sometimes  neces- 
sary to  collect  the  bud  wood  during  the  previous  winter  and  hold  it 
dormant  in  cold  storage  until  needed.  In  California,  the  season  is 
long  enough  to  permit  the  budding  of  peaches  and  sometimes  of  other 
stone  fruits  in  the  usual  way  in  May  or  June,  just  as  soon  as  the 


Circ.  294] 


PROPAGATION    OF    DECIDUOUS   FRUITS 


seedling  stock  is  large  enough  and  the  new  growth  on  the  trees 
sufficiently  matured  for  buds  to  be  secured.  June  buds  must  be 
forced  into  quick  growth  by  partially  breaking  off  the  tops  of  the 
little  trees.  As  soon  as  the  buds  begin  to  open,  the  entire  tops  are 
removed. 

Flute  and  Ring  Budding. — Other  types  of  budding  sometimes  used 
on  the  Pacific  Coast  are  flute  and  ring  budding.  Flute  budding  is 
adapted  to  plants  having  thick  bark,  like  the  walnut  or  pecan,  and 


Vrowc^XV^ 


$AY\C^  N?)vaA 


1 1-1 


Fig.  3. — Special  forms  of  buds.     The  ring  and  flute  buds  are  used  in 
propagating  walnut,  pecan  and  other  thick-barked  trees. 


is  usually  done  when  the  bark  peels  best.  By  this  method,  a  section 
of  bark  is  removed  from  the  seedling  and  replaced  by  a  similar  portion 
including  the  bud  desired.  The  bud  is  not  held  under  flaps  of  bark 
as  in  shield  budding  but  is  tied  to  the  stock  in  much  the  same  manner. 
When  the  operation  extends  entirely  around  the  stem,  it  is  called 
"ring  budding." 

Prong  Budding. — Another  modification  of  shield  budding  is  prong 
budding.  The  method  is  very  similar  to  grafting.  Instead  of  a  simple 
bud,  a  short  spur  is  used.  The  spur  with  a  slice  of  bark  is  removed 
much  like  a  shield  bud,  but  only  when  the  wood  is  dormant.  After 
the  operation  is  completed,  the  seedling  is  cut  off  just  above  the 
inserted  bud  (spur)  and  the  wound  covered  with  grafting  wax 
(fig.  3). 

GRAFTING 

The  different  ways  of  grafting  are  usually  given  names  according 
to  the  position  of  the  union  on  the  plant  and  the  method  of  joining 
stock  and  scion.    There  are  four  general  classes :  root  grafting,  crown 


8  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

grafting,  stem  grafting,  and  top  grafting.  The  part  that  is  grafted 
on  is  known  as  the  stock  and  the  scion  is  a  section  of  a  one-year-old 
twig  that  is  joined  to  the  stock. 

Root  Grafting. — In  the  Eastern  and  Central  states,  root  grafting 
sometimes  called  "bench  grafting,"  is  a  popular  method  of  propa- 
gating apples  and  pears.  One-year-old  seedling  trees  are  taken  up 
from  the  nursery  as  soon  as  dormant,  tied  in  bundles  of  100  each. 
Nurserymen  carefully  grade  the  trees  according  to  size.  Those  taller 
than  twelve  inches  are  shortened  by  removing  the  tops  to  within  four 
inches  of  the  roots.  The  bundles  are  kept  in  good  condition  until 
needed  by  burying  in  sand  or  green  sawdust  in  a  cellar  or  cool  room 
or,  by  selecting  a  moist,  well-drained  place  out-of-doors  and  "  heeling  - 
in. "  Scions  of  the  desired  varieties  are  cut  after  the  leaves  have 
dropped,  and  are  stored  in  moist  sand  in  a  cool  room ;  the  grafting  is 
done  indoors  during  winter.  A  straight,  thin  blade  that  will  hold  a 
fine  edge  makes  a  good  grafting  knife.  Some  propagators  prefer  to 
cut  down  the  blade  of  an  old-fashioned  steel  case-knife  about  three 
inches  in  length  and  grind  it  sharp  for  a  grafting  knife. 

The  entire  root  may  be  grafted  or  it  may  be  cut  into  several  pieces 
and  each  portion  grafted  to  a  scion.  Whole  roots  do  not  require 
scions  of  more  than  two  buds  but  the  scions  are  usually  about  four 
inches  long.  Piece  roots  may  be  from  one  to  four  inches"  in  length. 
Where  stock  is  scarce  and  scion  wood  plentiful,  a  short  piece  root  and 
a  long  scion  are  often  used.  The  union  is  then  set  deeper  in  the  soil. 
A  3-inch  piece  root  is  usually  joined  to  a  6  or  7-inch  scion,  giving 
grafts  8  or  9  inches  in  length  or  more. 

The  '"whip  graft"  is  commonly  used.  At  the  base  of  the  scion 
and  top  of  the  root,  sloping  cuts  1  to  1%  inches  are  made.  On  each 
of  these  cuts,  starting  at  a  point  about  one-third  from  the  tip,  a 
reverse  cut  is  made,  slightly  curved  and  parallel  to  the  first  cut.  A 
thin  tongue  of  wood  in  both  root  and  scion  is  thus  formed,  which, 
when  skillfully  made,  will  interlock  and  fit  snugly  together  (fig.  4). 
Care  should  be  taken  to  see  that  the  cambium  layers  (inner  bark)  of 
the  scion  and  root  fit  together  on  at  least  one  side.  If  one  piece  is 
larger  than  the  other,  they  will  coincide  or  fit  only  on  one  side  but, 
fortunately,  this  is  sufficient. 

The  parts  are  held  in  place  with  a  few  wraps  of  waxed  string. 
A  good  wrapping  thread  is  made  by  dropping  a  ball  of  No.  18  knitting 
cotton  into  melted  grafting  wax,  afterwards  allowing  it  to  drain  and 
cool.  No  tying  is  needed  with  waxed  string.  Heavy  cord  which  does 
not  rot  readily  in  the  soil  might  constrict  the  growing  graft.  After 
being  joined  and  tied,  the  grafts  are  placed  in  moist  sand,  sawdust, 


Circ.  294] 


PROPAGATION    OF    DECIDUOUS   FRUITS 


or  moss  and  kept  cool  until  planting  time.  Growth  at  the  juncture 
of  scion  and  root  has  then  started  and  a  strong  union  soon  results. 

In  large  nurseries  a  furrow  may  be  plowed  six  or  eight  inches  deep 
and  the  grafts  set  six  to  eight  inches  apart.  Small  plantings  may  be 
made  with  a  spade.  The  soil  should  be  firmed  well  around  each 
graft,  especially  around  the  root  part. 

Crown  Grafting. — Some  propagators  bud  all  of  their  apple  and 
pear  seedlings  and  "whip  graft"  or  "cleft  graft"  wherever  the  buds 
fail  to  unite.  The  latter  is  done  in  the  early  spring  as  the  trees  stand 
in  the  nursery  row. 


toiroo^tk 


\JLxvOl 


Fig.  4. — Root-graft.  This  manner  of  uniting  scion  and  stock  is  often  known 
as  the  "whip"  or  "tongue"  graft.  It  is  not  much  used  in  California  but  is 
extensively  employed  in  cold  climates  where  work  is  done  indoors  during  the 
winter. 


In-laying,  a  special  form  of  crown  grafting,  is  sometimes  done  at 
or  just  above  the  surface  of  the  ground.  The  stock  is  cut  off  and  on 
the  stump  a  V-shaped  groove  made  either  with  a  sharp  knife  or  with 
a  special  tool,  which  will  cut  both  the  groove  and  a  triangular-shaped 
wedge  at  the  base  of  the  scion  to  fit  the  groove.  The  scion  is  held  in 
place  with  a  waxed  cloth  or  string. 

Stem  Grafting. — A  common  method  of  inserting  a  scion  in  the 
trunk  or  stem  below  the  framework  branches  is  known  as  "stem 
grafting,"  and  is  accomplished  by  making  use  of  a  side  graft.  With 
a  sharp  chisel  an  oblique  cut  about  an  inch  deep  is  made  in  the  stock 
and  the  scion  cut  wedge-shaped  to  fit.  The  wound  is  covered  with 
wax  or  waxed  cloth  (fig.  5). 

Inarching. — Another  method  of  stem  grafting  is  that  known  as 
"grafting  by  approach"  or  "inarching."     One  plant  can  be  made 


10 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


to  unite  with  another  while  both  are  growing  on  their  own  roots.  This 
is  often  practiced  with  pear  trees  on  undesirable  roots  or  where  the 
trunk  has  been  injured  by  blight  or  rodents. 

A  seedling  of  the  favored  stock  is  planted  by  the  side  of  the  tree 
and  grafted  into  the  latter  four  to  six  inches  (or  as  low  as  possible) 
from  the  ground.  The  seedling  is  whittled  to  a  wedge-shape  and 
inserted  in  a  cut  made  with  a  knife  point  or  thin  chisel.  The  parts  are 
firmly  wrapped  and  waxed  until  they  unite.     Several  seedlings  may 


Fig.  5. — Side-graft.     Left,  scion  set  in  stock;   center,  the  scion; 
right,  graft  wrapped  with  waxed  cloth. 


be  thus  grafted  around  a  tree  and  serve  either  to  bridge  over  a  crown 
wound  or  to  revive  the  tree  by  providing  a  more  congenial  stock.  It 
is  easier  to  do  the  grafting  and  waxing  before  planting  the  seedlings. 
The  seedlings  should  be  planted  as  closely  to  the  trees  as  possible 
(much  closer  than  those  shown  in  the  illustration)  to  avoid  injury  in 
cultivating.  Oftentimes  valuable  trees  can  be  saved  by  inarching  with 
very  little  setback  in  their  growth  (fig.  6). 

Bridge  Grafting. — Each  year  many  orchard  trees  on  the  Pacific 
Coast  are  severely  injured  or  killed  by  rodents  or  through  mechanical 
injuries  which  result  in  the  girdling  of  the  trunk.  Fortunately  such 
injuries  usually  occur  in  winter  when  the  trees  suffer  least.  By 
bridging  over  the  injured  area,  the  tree  can  be  made  to  function 
normally.  Scions  two  or  three  inches  apart  are  inserted  into  the  live 
tissues  above  and  below  the  wound. 


Circ.  294] 


PROPAGATION    OF    DECIDUOUS   FRUITS 


11 


The  operation  is  quite  simple.  Dead  and  loose  bark  should  be  cut 
away,  and  the  wound  smoothed  and  treated  with  a  good  antiseptic. 
The  scions  for  the  bridge  should  be  of  the  previous  season's  growth 
and  of  the  same  species  as  the  tree  to  be  treated.  The  two  ends  of 
the  scion  are  whittled  to  a  long,  thin  wedge  on  the  same  side.  A  single 
shallow  stroke  of  the  knife  will  give  the  necessary  flat  surfaces  to  the 
other  side.  The  wedge-shaped  ends  are  slipped  into  slits  made  in 
the  bark,  or  under  the  edges  of  the  bark,  above  and  below  the  girdle, 
so  that  the  cambium  layers  of  scion  and  stock  are  in  contact.     The 


Fig.  6.  Inarching.  These  young  trees,  girdled  by  gophers  at  the  ground, 
were  saved  by  inarching  with  seedling  trees.  The  seedlings  were  planted 
unnecessarily  far  from  the  trees  and  are  likely  to  be  in  the  way  of  cultivation. 


scions  should  be  slightly  longer  than  the  space  to  be  bridged,  so  that 
when  forced  into  place  the  tension  will  hold  them  in  place  (fig.  7).  It 
is  a  good  plan  to  wrap  waxed  cloth  over  the  edges  of  the  bark  covering 
the  scions  or  to  drive  a  small  nail  through  the  ends  of  each  scion  to 
hold  them  firmly  in  position.  If  the  girdle  is  near  the  ground,  it  is 
well  to  bank  soil  over  the  bridge  grafts  to  keep  them  from  drying  out. 

Sometimes  suckers  from  the  root  inserted  above  a  trunk  would 
serve  the  same  purpose  as  scions.  When  this  method  is  possible,  it  is 
usually  a  very  successful  one  (fig.  8). 

Top  Grafting. — Top  grafting  is  a  popular  method  of  changing 
varieties  of  deciduous  fruit  trees.     The  work  is  usually  done  during 


12 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


the  dormant  season,  but  with  some  fruits  may  be  successfully  per- 
formed as  late  as  the  blooming  period,  if  the  scions  have  been  kept 
dormant  in  cold  storage. 

Tools  for  cleft  grafting  are  inexpensive  and  simple.  An  old 
hatchet,  ground  sharp,  a  short  wooden  club  of  hardwood  for  a  mallet, 
and  wedges  of  hardwood  or  steel  are  very  serviceable  for  a  few  trees. 
For  extensive  operations,  a  grafting  tool  with  steel  splitting  blade  and 
wedge  attached  to  one  handle  is  more  convenient.  This  may  be  pur- 
chased from  a  hardware  dealer.  A  tool  less  artistic  in  appearance,  but 
usually  more  durable,  can  be  made  by  a  blacksmith  from  an  old  file 

or  rasp.  The  cutting  edge  should  be  con- 
cave to  prevent  peeling  the  bark  when 
the  wood  is  split. 

Cleft  Grafting. — A  common  form  of 
top  grafting  is  known  as  the  cleft  graft. 
Branches  of  the  stock  are  sawed  off  six 
to  twelve  inches  above  the  trunk.  A 
sharp  saw  is  essential  for  a  clean  cut.  It 
is  good  practice  to  smooth  the  rough 
edges  of  the  bark  with  a  sharp  knife  to 
induce  ready  healing  of  the  wounds. 

The  grafting  tool  is  placed  across  the 
flat  surface  of  the  stub  (preferably  not 
through  the  exact  center)  and  driven 
into  it  two  or  three  inches  deep  with  the 
mallet.  A  sharp  blow  from  underneath 
will  loosen  the  tool,  and  a  wedge  may 
then  be  driven  into  the  cleft  to  hold  it 
open  while  the  scions  are  inserted  (fig. 
9).  Scions  three  to  four  inches  in  length  with  two  or  three  buds  are 
best,  as  long  scions  are  often  loosened  by  the  wind.  Two  sloping  cuts, 
1%  to  2  inches  in  length  are  made  at  the  base  of  each  scion  to  form  a 
wedge  which  is  thin  on  one  side  and  thicker  on  the  other,  like  a  knife 
blade.  Two  scions  are  inserted  in  each  cleft  (one  on  each  side)  so  that 
the  thin  edge  fits  neatly  into  the  opening  and  the  bark  side  comes  in 
line  with  the  inside  of  the  bark  of  the  stock.  If  the  scions  are  pointed 
slightly  outward  and  set  firmly  in  the  cleft,  the  cambium  layer  should 
come  in  direct  contact  with  the  same  tissue  of  the  stock  and  union 
should  take  place  readily  (fig.  10). 

After  the  scions  are  inserted,  the  wedge  is  removed  and  the 
exposed  surface  covered  with  grafting  wax,  waxed  cloth,  or  melted 
asphaltum.     Where  there  is  danger  of  crushing  the  scions,  wads  of 


S*o  Ok 


Fig  7. — Bridge  grafting.  If 
trees  are  wounded  during  the 
dormant  season  the  injury  may 
be  repaired  in  early  spring  by 
bridging  with  several  scions  as 
shown  in  the  illustration. 


Circ.  294] 


PROPAGATION    OF    DECIDUOUS    FRUITS 


13 


newspaper  may  be  pushed  into  the  cleft  to  relieve  the  side  pressure 
or  a  wooden  wedge  may  be  driven  in  and  broken  off  flush  with  the 
surface. 

Saw-kerf  Graft. — In  some  orchards  the  saw-kerf  graft  is  used. 
The  branches  are  cut  off  just  as  for  cleft  grafting,  but  the  stub  is  not 
split.  Instead,  a  notch  is  cut  down  the  side  of  the  stub  with  a  saw 
and  the  edges  smoothed  with  a  sharp  knife.  The  scion  is  cut  to  fit 
the  notch  and  is  set  in  and  waxed  over  in  a  manner  similar  to  that  for 
cleft  grafting.  Some  propagators  slope  the  tip  of  the  scions  inward 
rather  than  outward,  as  in  this  position  they  are  less  liable  to  be 


Fig.  8. — Bearing  pear  trees  injured  by  blight  were  saved  by  grafting  in 
root  suckers  on  trunk  and  branches  above  injury. 


dislodged  by  wind  and  birds  (fig.  11).  The  saw-kerf  graft  is  prefer- 
able to  the  cleft  graft  for  branches  larger  than  four  inches  in  diameter 
as  the  wounds  heal  quicker. 

A  very  practical  modification  of  the  saw-kerf  method  consists  in 
sawing  notches  %  of  an  inch  deep  directly  into  the  stump  by  holding 
the  saw  at  an  angle  of  forty-five  degrees.  The  saw  should  have  coarse 
teeth  or  a  heavy  '"set"  so  that  the  kerfs  (slits)  are  from  %  to  %6  of 
an  inch  wide.  If  they  are  made  an  inch  apart  all  around  the  stump 
no  time  need  be  devoted  to  smoothing  them  with  a  knife  as  enough  of 
the  scions  will  grow  to  make  the  operation  a  success  and  the  work  is 
very  quickly  done.     The  scions  must  be  flattened  on  both  sides  but 


14 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


with  one  edge  thicker  than  the  other.  A  little  practice  will  enable  the 
operator  to  make  them  fit.  Complete  the  operation  by  sealing  up  all 
wounds  with  grafting  wax. 


Fig.   9. — Cleft-graft.     Left,   stock   split  with  grafting  tool; 
right,  cleft  open  ready  for  inserting  scions. 


Fig.  10. — Cleft-graft.     Left,  scions  set;  center,  the  scions: 
right,  completed  graft  covered  with  grafting  wax. 


Bark  Graft. — Bark  grafting  is  a  form  of  top  grafting  often  used 
with  old  trees.  The  top  is  cut  off  as  for  cleft  grafting,  and  the  edge 
of  the  stub  smoothed  with  a  knife.  Instead  of  splitting  or  notching 
the  stock,  the  bark  is  loosened  with  a  thin  chisel  or  knife  blade  and 
wedge-shaped  scions  forced  beneath  the  bark  and  wood.  Sometimes 
a  shoulder  is  cut  on  the  scions  to  hold  them  in  place.    Either  grafting 


CIRC.  294]  PROPAGATION    OF   DECIDUOUS   FRUITS  15 

wax  or  waxed  cloth  is  used  to  cover  and  seal  wounds  until  union  takes 
place  (fig.  12). 

With  some  fruits,  bark  grafting  is  often  more  successful  than  cleft 
grafting.  Some  propagators  like  best  to  top  graft  only  part  of  the 
branches  one  year,  leaving  the  remainder  uncut  to  provide  shade  for 
the  scions  and  foliage  for  the  manufacture  of  plant  food  for  the  tree 
while  the  scions  are  uniting  and  putting  out  new  leaves.  Others  graft 
the  entire  top  at  one  time,  allowing  a  few  water  sprouts  to  form  on 
the  trunk  the  first  season  to  produce  foliage  until  the  scions  are 
established. 


u  Cv.o*w 


Fig.  11. — Saw-kerf  graft.  Left,  scion  set;  center,  notch  smoothed  with  a 
knife;  right,  shows  position  of  saw.  A  modification  of  this  method  consists  of 
making  a  single  cut  into  the  wood  an  inch  deep  with  a  coarse-toothed  saw. 

Top  Budding. — This  form  of  top-working  is  convenient  for  chang- 
ing over  undesirable  trees  of  peaches  as  all  peach  trees  are  difficult 
to  graft.  The  top  is  cut  back  severely  when  dormant  and  the 
resultant  new  growth  is  budded  the  following  summer.  The  T-bud 
form,  as  for  shield  budding  in  the  nursery,  is  commonly  used.  Buds 
of  the  desired  variety  are  cut  from  well  hardened  wood  of  the  current 
season's  growth.  The  method  of  setting  and  wrapping  the  buds  is 
similar  to  that  used  in  shield  budding. 

Grafting  Waxes  and  Wrapping. — A  much  used  grafting  wax  is 
made  by  melting  together  four  parts  of  resin,  two  parts  of  beeswax, 
and  one  part  of  tallow.  While  warm  this  may  be  applied  with  a 
brush  to  the  cut  surfaces  of  the  stock,  or  if  made  by  the  process  of 
cooling  the  molten  mass  by  pouring  into  cold  water,  the  wax  may  be 


16 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


pulled  like  taffy  until  smooth  and  tough  and  then  rolled  into  balls  and 
laid  away  on  oiled  paper  until  needed.  Before  handling  in  this  way, 
the  hands  should  be  greased  with  tallow  or  lard.  This  makes  a  soft 
wax  which  can  be  warmed  by  simply  working  with  the  hands  or  if 
needed  in  a  hurry  may  be  heated  over  a  fire.  The  wax  should  be 
carefully  spread  over  all  cuts,  cracks,  and  exposed  places  on  the  graft. 
Waxed  cloth  is  made  in  the  same  manner  as  waxed  thread  (p.  9). 
Strips  of  old  sheeting  or  similar  cloth  are  rolled  loosely,  dropped  in 
hot  wax  for  a  few  minutes,  and  then  set  away  on  greased  paper  to 
drain.     Waxed  string  or  cloth  may  be  kept  indefinitely.     It  is  easily 


Fig.  12. — Bark  graft.     Left,  scions  set;  center,  the  scions; 
right,  graft  wrapped  with  waxed  cloth. 

softened  if  the  wax  becomes  hard,  by  dipping  in  warm  water.  During 
the  past  few  years  many  orchardists  have  successfully  substituted 
asphaltum  Grade  D  for  grafting  wax.  It  is  much  less  expensive  and, 
when  melted,  is  as  easily  applied  with  a  brush. 

Grafting  pots  or  portable  hand  stoves  for  heating  the  wax  may  be 
secured  through  dealers  in  hardware  and  orchard  supplies.  For 
grafting  a  few  trees  the  wax  may  be  poured  into  a  tin  can  and  kept 
soft  by  placing  it  in  a  pail  half -filled  with  hot  coals. 


HARDWOOD    CUTTINGS 

A  hardwood  cutting  is  a  portion  of  the  ripened  wood  of  a  plant  of 
the  previous  season's  growth.     Such  fruits  as  grape,  currant,  goose- 


CIRC.  294]  PROPAGATION    OF    DECIDUOUS   FRUITS  1? 

berry,    fig,    and    quince    are    ordinarily    propagated    by    this    simple 
method. 

It  is  impossible  to  lay  down  a  hard  and  fast  rule  for  the  length  of 
cuttings  or  the  number  of  nodes,  that  is,  buds  or  joints,  on  each.  A 
cutting  of  currant  and  gooseberry  six  or  eight  inches  in  length  will 
contain  several  nodes,  while  one  of  grape  of  the  same  length  may 
have  only  two.  Cuttings  are  usually  about  six  inches  in  length  and 
contain  two  or  more  nodes.  Grape  propagators  prefer  a  10  or  12-inch 
cutting  with  three  nodes.  As  roots  generally  develop  best  from  the 
vicinity  of  the  buds,  it  is  the  usual  practice  in  preparing  cuttings  to 
make  the  lower  cut  just  below  a  node  or  bud  (fig.  13). 

Some  propagators  use  a  heel  or  mallet  cutting.  The  former  is  made 
with  a  slice  of  the  old  wood  adhering  to  the  base,  and  the  latter  with 
a  short  section  (one-half  to  one  inch)  of  the  parent  stem  left  intact. 
Roots  develop  readily  on  such  cuttings,  but  they  are  more  wasteful  of 
wood,  since  only  the  base  of  the  shoot  is  used  for  each  cutting.  Other 
propagators  prefer  "single  eye"  cuttings  with  only  one  bud  and  an 
inch  of  wood  above  and  below  it.  Though  this  method  gives  a  large 
number  of  cuttings  from  a  limited  supply  of  wood,  it  is  usually  neces- 
sary to  start  them  in  a  greenhouse  or  hotbed  with  bottom  heat.  The 
bud  is  placed  in  either  an  upright  or  a  horizontal  position  about  an 
inch  below  the  surface  of  the  soil  or  sand  and  kept  moist  (fig.  14). 

The  cuttings  are  usually  made  in  late  fall  before  heavy  frosts. 
They  are  tied  in  bundles,  packed  in  sand,  moss,  or  green  sawdust  and 
stored  in  a  cool  cellar  or  pit  during  the  winter.  In  the  early  spring 
the  bundles  are  opened  and  the  cuttings  set  two  or  three  inches  apart 
in  the  nursery  row.  Cuttings  difficult  to  root  should  be  placed  in  a 
coldframe  or  sand  bed  in  an  upright  but  inverted  position,  and  the 
upper  end  of  the  bundles  covered  with  an  inch  of  sand.  Leaves  or 
manure  spread  over  the  cuttings  will  protect  them  from  freezing. 
Early  in  the  spring  the  litter  may  be  taken  off  and  the  sand  bed  or 
frame  covered  with  a  glass  sash.  This  method  keeps  the  tops  of  the 
cuttings  cool  and  dormant  while  the  butts,  being  nearer  the  surface  of 
the  sand,  receive  more  warmth.  These  callus  quickly  and  roots  start 
before  the  leaves  appear.  The  cuttings  are  then  in  ideal  condition  for 
setting  in  the  open  ground. 

In  milder  localities  of  the  Pacific  Coast,  hardwood  cuttings  of  many 
plants  may  be  made  and  set  directly  in  the  nursery  row  in  the  late  fall 
or  winter  after  the  wood  is  ripened.  Roots  will  form  during  the  early 
spring,  and  strong  young  plants  will  be  ready  for  field  setting  the  next 
fall  or  the  following  spring.  Care  should  be  taken  to  place  the  cuttings 
in  soil  which  is  not  apt  to  heave  by  freezing  and  thawing  or  in  which 


18 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


water  stands  for  more  than  a  day  or  two  at  a  time  even  after  heavy 
rains.  Leaves  or  straw  as  a  thin  top  mulch  usually  prevents  injury 
from  freezing.  If  not  protected  in  some  manner,  the  cuttings  should 
be  carefully  watched;  if  the  soil  about  them  becomes  displaced,  they 
should  be  reset  and  packed  firmly  again  in  fine  soil. 

All  cuttings  should  be  planted  two  or  three  inches  apart  in  the 
nursery  row  with  the  uppermost  bud  just  above  the  ground.  A  furrow 
may  be  opened  with  a  plow,  the  cuttings  placed  against  the  land  side, 
and  loose  soil  packed  firmly  around  them,  or  they  may  be  planted  in 
an  opening  made  with  a  garden  dibble  or  spade.  Very  long  cuttings 
are  best  set  on  a  slant  so  the  lower  nodes,  where  the  roots  are  expected 


C<xYVas 


Fig.    13. — Hardwood    cuttings 
showing  callus  and  root  formations. 


Fig.  14. — Special  forms  of  hard- 
wood cuttings. 


to  form,  will  be  nearer  the  surface  of  the  soil  and  receive  more  warmth. 
Care  should  be  taken  that  the  soil  is  firmed  well  around  each  cutting, 
especially  at  the  base. 

LAYERING 

Layering  is  the  operation  of  rooting  stems  while  they  are  attached 
to  the  parent  plant.  This  is  a  simple  method  of  propagation,  as  the 
parent  plant  nourishes  the  layered  parts  until  they  are  well  rooted. 

Tip  Layering. — Some  plants  root  best  by  layering  the  tips,  while 
others  seem  able  to  strike  root  at  any  point  on  the  new  wood.  In 
jointed  plants  like  the  grape,  the  roots  form  at  the  nodes  or  joints. 
By  wounding  the  bark  by  scraping,  cutting  or  sharply  twisting  the 
stem,  older  wood  may  be  induced  to  root. 

Loganberries,  black  raspberries  (blackcaps),  dewberries,  and  trail- 
ing blackberries  are  commonly  propagated  by  bending  down  a  cane 


Circ.  294] 


PROPAGATION    OF    DECIDUOUS   FRUITS 


19 


of  the  previous  season's  growth  and  covering  the  tip  with  two  or  three 
inches  of  fine  moist  soil.  In  windy  localities  it  is  best  to  dig  shallow 
holes  near  the  parent  plant,  insert  the  cane  tips  and  press  the  soil 
firmly  around  them  to  insure  a  good  root  system.  This  is  done  when 
the  young  cane  has  stopped  growth  in  early  fall.  Roots  quickly 
develop  on  the  buried  tip,  and  by  early  winter  the  layers  are  ready 
for  transplanting.  Before  digging  up,  the  cane  is  severed  from  the 
parent  plant,  six  to  eight  inches  being  left  attached  to  the  rooted  tip 
(fig.  15).  Well  rooted  tips  can  be  field  set  any  time  during  the 
dormant  season.  In  California  they  move  well  in  January  or 
February. 


^OO^^T\0«. 


fiicGj'S-Z  * 


&:***& 


Fig.  15. — Layered  loganberry.     The  cane  tips  were  lightly  covered 
with  soil  in  early  fall. 

Mound  Layerage. — Plants,  like  currants  and  gooseberries,  which 
"stool"  are  often  propagated  by  mound  layering.  In  the  fall  after 
the  growing  season,  new  shoots  are  bent  outward  and  moist  soil 
mounded  over  the  crown  of  the  parent  plant  at  the  base  of  the  shoots, 
the  latter  being  wounded  by  scraping  with  the  spade  at  points  where 
roots  are  desired.  When  well  rooted,  the  shoots  may  be  severed  from 
the  parent  plant,  saving  as  much  of  the  new  root  system  as  possible 
(fig.  16). 

This  method  of  propagation  is  more  expensive  than  that  by  hard- 
wood cuttings,  since  only  one  new  plant  can  be  secured  from  each 
shoot,  but  it  is  a  sure  method  of  propagating  gooseberries,  which  are 
sometimes  difficult  to  root  from  cuttings. 

Vine  Layering. — The  grape  can  easily  be  propagated  by  laying 
down  a  young  shoot  and  covering  one  or  more  buds  with  soil.  During 
late  fall  or  winter  when  the  vines  are  dormant,  a  shallow  trench  is 


20 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT   STATION 


dug  where  a  new  plant  is  desired  and  in  it  is  laid  a  shoot  from  a  plant 
nearby.  Two  or  three  buds  are  covered  with  moist  soil,  and  when 
a  good  root  system  is  developed,  the  shoot  is  severed  from  the  parent 
vine.  A  wire  twisted  around  the  shoot  just  below  the  buried  bud 
nearest  the  parent  plant  will  constrict  the  backward  movement  of  sap 
and  often  aid  in  root  formation  (fig.  17). 


Fig.  16. — Sprouts  from  a  currant  being  caused  to  root  by  means  of 
mound  layerage. 


Shrubby  plants  of  all  kinds  with  branches  or  sprouts  long  enough 
to  reach  the  ground  may  be  layered  in  like  manner.  The  tips  must  not 
be  covered  but  the  layered  part  should  be  buried  deeply  enough  to 
be  in  contact  with  moist  soil  all  summer. 

Runners. — Quite  similar  to  vine  layering  is  the  method  by  which 
the  strawberry  is  propagated.  Runners  develop  from  the  mother 
plant ;  at  each  second  joint  new  plants  will  form.  Most  strawberry 
varieties  produce  an  abundance  of  runner  plants  without  assistance. 
Small  mounds  of  soil  or  clods  placed  on  the  second  and  fourth  joints 
will  hold  down  the  runners  and  aid  in  the  formation  of  new  plants. 
Those  nearest  the  mother  plants  are  strongest  and  are,  therefore,  the 
most  desirable  for  field  setting.     Plants  of  the  previous  season  are 


CiRC.  294] 


PROPAGATION    OF   DECIDUOUS   FRUITS 


21 


preferable  to  older  plants  for  planting.  It  is  better  to  set  a  field 
with  runner  plants  from  a  young  plantation  than  from  an  old  field, 
as  the  runners  are  usually  strong  and  the  plants  not  likely  to  be 
diseased  or  infested  with  insects  (fig.  18). 

ROOT    SUCKERS 

Red  raspberries  and  bush  (upright)  blackberries  are  commonly 
propagated  by  underground  shoots  or  root  suckers  on  which  upright 
stems  with  roots  are  formed.  Cutting  through  the  sprouted  root  with 
a  sharp  spade  separates  the  new  plant  from  the  mother  plant.  Young 
fields  produce  more  and  stronger  plants  than  old  fields  (fig.  19). 

Root  Cuttings. — Berries  or  other  fruits  that  sprout  readily  usually 
may  be  propagated  by  root  cuttings.    The  roots  are  dug  up,  cut  into 


Fig.  17. — Layerage.     A  convenient  way  to  propagate  grapes, 
roses  and  shrubbery. 

pieces  two  or  three  inches  in  length,  and  planted  in  early  spring ;  but 
it  requires  a  year  longer  to  secure  good  plants  by  this  method  than  by 
setting  sucker  plants.  Root  cuttings  are  placed  in  a  nursery  row  in 
a  trench  three  or  four  inches  deep  and  covered  with  fine  moist  soil. 
After  a  year's  growth,  they  may  be  reset  in  a  permanent  field. 


SEEDS 

One  method  of  starting  seeds  for  budding  or  grafting  is  to  sow  the 
pits  or  seeds  from  ripe  fruits  directly  in  the  nursery  row  or  garden 
after  the  flesh  has  been  removed  and  the  surface  moisture  dried.  The 
soil  is  kept  moist  and  sometimes  covered  with  a  mulch  of  leaves  to 
prevent  baking  the  surface.     This  method  is  successful  only  where 


22 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


the  soil  is  well  drained  and  the  moisture  is  controlled.  Field  mice  are 
fond  of  some  fruit  seeds,  especially  apple,  and  may  destroy  much  of 
the  seed  bed  during  the  winter  (fig.  20). 

A  common  method  of  sprouting  the  seeds  or  breaking  their  seed 
coats  is  to  stratify  them  for  two  or  three  months  during  the  fall  and 
winter  before  planting  in  the  nursery.  About  November  alternate 
layers  of  moist  sand  and  seeds  from  ripe  fruits  are  placed  in  shallow 
boxes  and  kept  in  a  cool  place  until  late  winter.  It  is  often  necessary 
to  cover  the  box  or  seed  pit  with  screen  wire  for  protection  against 


Fig.  18. — Strawberry  and  runner  plants. 

birds  or  squirrels.  In  January  or  February  the  seeds  are  examined 
from  time  to  time  and  when  they  begin  to  crack  or  start  to  sprout 
they  are  planted  in  the  nursery  row  to  be  budded  the  following 
summer.  When  large  quantities  of  peach  or  other  large  seeds  are 
stratified  a  pit  may  be  dug  twelve  or  eighteen  inches  deep  in  well 
drained  soil.  The  pit  is  filled  with  seeds  and  covered  with  a  few 
inches  of  moist  sand  (fig.  21). 

Peach  and  apricot  pits  on  the  Pacific  Coast  are  usually  secured 
from  canneries  or  dry  yards  and  are  in  a  more  or  less  dried  condition 
when  they  reach  the  propagator.  Drying  of  the  outer  hard  seed  coat 
does  not  interfere  with  germination.  The  kernel,  however,  should  not 
become  too  dry. 

Cherry  seeds  should  dry  only  in  the  shade  before  being  stratified. 
Some  successful  propagators  bury  the  cherry  pits  in  a  trench  at 
harvest  time  and  keep  them  covered  with  moist  soil  until  late  fall, 
then  stratify  them  in  the  usual  method. 

Apple  and  pear  seeds  should  be  carefully  watched  in  the  strati- 
fying box  and  planted  before  the  sprouts  appear.  Peaches  can  be 
planted  and  will  grow  after  the  sprouts  have  started  but  apples  and 
pears  will  not. 


Circ.  294] 


PROPAGATION    OF    DECIDUOUS   FRUITS 


23 


Seeds  that  are  not  apt  to  be  molested  by  mice,  such  as  the  peach, 
apricot  and  walnut,  may  be  planted  in  the  late  fall,  but  in  general  it 
is  preferable  to  stratify  all  seeds  over  winter,  and  plant  them  in  late 
January  and  February  according  to  the  needs  of  the  various  seeds. 
In  a  small" way  seeds  are  best  mixed  with  sand  in  "flats"  (shallow 
boxes)  with  open  tops  and  kept  on  the  ground  in  a  shady  place  out 
in  the  open  all  winter.  Rains  are  frequent  enough  to  keep  the  sand 
moist. 


New  9\<KV* 


Fig. 


19. — Eoot  suckers.     New  plants  spring  up  from  the  roots  of  red 
raspberries,  blackberries  and  many  other  plants. 


There  are  two  plans  for  planting ;  in  seed  beds,  and  in  nursery  rows. 
Nurserymen  usually  prefer  to  grow  apples,  pears,  and  cherries  in  a 
seed  bed  for  one  season  and  then  cut  the  seedlings  back  and  trans- 
plant them  to  the  nursery  where  they  are  grown  another  season  and 
are  budded  during  late  summer  of  that  season.  The  other  plan,  which 
is  generally  followed  by  beginners,  is  to  plant  the  seed  directly  in  the 
nursery  rows  with  the  idea  of  giving  the  seedlings  extra  good  care  as 
to  irrigation  and  cultivation  so  they  will  be  large  enough  to  bud  the 
same  season. 

Under  the  first  plan  the  seeds  may  be  planted  in  low  raised  beds 
six  to  eight  feet  wide  and  any  length  desired.    Apple,  pear,  plum  and 


24 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


cherry  seeds  are  planted  thickly,  as  crowding  is  desirable  to  prevent 
the  seedlings  from  becoming  too  large.  For  lining  out  in  the  nursery 
row,  they  are  cut  back  to  five  or  six  inches,  set  eight  to  ten  inches 


Fig.  20. — Seed  stratified  in  sand  box.     Any  seeds,  in  a  small  way, 
may  be  treated  in  this  manner. 


Fig.  21. — Peach  seed  stratified  in  pit. 

apart,  and  budded  the  following  July  or  August.  Peaches,  apricots, 
and  almonds  are  rarely  ever  transplanted,  as  they  grow  large  enough 
to  be  budded  the  first  season.  They  are,  therefore,  always  planted  in 
the  nursery  row  in  the  first  place.  If  not  crowded  in  the  row  it  is 
quite  possible  to  treat  apple,  pear  and  cherry  seedlings  in  the  same 
manner. 

To  grow  seedlings  to  budding  size  in  one  season  requires  that  the 
nursery  soil  be  put  in  the  finest  state  of  tilth  possible  before  the  seeds 
are  sown.  During  the  growing  season,  the  nursery  will  have  to  be 
watered  according  to  its  needs.  Sandy  soils  may  require  irrigating 
as  often  as  every  ten  days  or  two  weeks.  The  seedlings  should  not  be 
allowed  to  stop  growing. 


ACKNOWLEDGMENTS 


The  writer  is  indebted  to  Dr.  W.  L.  Howard  for  the  general  intro- 
duction, the  part  of  the  circular  relating  to  rootstocks,  and  assistance 
in  preparation  of  the  manuscript;  to  W.  J.  Norton  for  photographs 
on  inarching,  and  to  Miss  Edna  Russ  for  photographic  work. 


